The Muscular System
Review of Muscle Types
Characteristics
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Excitability
Contractibility
Extensibility
Elasticity
Functions
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Movement
Posture
Joint stability
Heat production
Whole muscle structure
Skeletal muscle attachment
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Direct attachment
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Indirect attachment
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Tendon
Aponeurosis
Skeletal muscle fiber (cell)
Muscle Contraction Stimulus
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Begins with stimulation of motor neurons
Sliding Filament Theory
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Impulse travels to axon terminal and
releases acetylcholine
Sarcolemma composition is altered and
sends message down T tubules to
release Ca2+
Increased calcium levels open myosin
binding sites on actin and ATP is broken
down to energize myosin
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Myosin binds to actin creating a cross
bridge resulting in a connection that
allows a “power stroke” to occur
ATP rebinds with myosin head, breaking
attachment
This process continues while calcium
and/or ATP levels are sufficient
Results in shortening of sarcomere
Sarcomere contraction video
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http://www.youtube.com/watch?v=83yNo
EJyP6g&feature=related
Substances used to provide energy
during muscle contraction
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ATP
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Creatine phosphate
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Fatty acids and glucose